Conventionally, as a molding device of this type, a loose core ejector device disclosed in, for example, Patent Document 1, is known. The loose core ejector device includes a core of a mold for forming an inner surface of an article to be molded; a loose core support rod which is movable, penetrating through this core, and disposed slantwise with respect to the core surface; a guide rod which is locked to a movable mold plate and a pedestal plate; and a slide base which is disposed in the sliding route of the ejector plate so as to be relatively slidable in relation to this guide rod, the loose core support rod being moved in conjunction with the movement of the slide base.
With such a loose core ejector device, one end of the guide rod is locked to a holder which is tightly fitted into a recess formed in the bottom face of the movable mold plate, and the loose core support rod is slidably inserted into an insertion hole which is formed in the core at practically the same inclination angle as that of the guide rod, the insertion hole providing only the element which determines the inclination angle of the loose core support rod.